Markforged Used a 3D Printed Soft Jaw to Make the First 25 Mark Ones

Wednesday, October 14, 2015

MarkForged Used a 3D Printed Soft Jaw to Make the First 25 Mark Ones

It happens to all of us. The first samples come in great. Then the production batch comes in fully machined, anodized, and wrong. It happened to us here at MarkForged with the first 25 machines we shipped. The 6061 aluminum milled fixture was wrong and we were right on top of a deadline. Here’s how we fixed it.

Of Course Something Broke at the Last Minute

A tool broke that carves the final radius in the pocket that holds the Z axis flag. We could have easily ground down the flag bases and sent out 25 almost-perfect, less-functional machines but that would have passed the problem along to our first users. That isn’t acceptable. We had to go back in and fix the pocket, ASAP.

This was early in the development of our Mark One printers so the few machines we had were running testing non-stop. It was hard to prioritize printing some tooling that might work over the print testing. But really, even we were just used to machining jaws from aluminum.

So we machined the first rework fixture out of 6061 and tried it. The jaw worked great until we realized it scratched the forward facing surface. Now we had another difficult choice – do we send out scratched, perfectly functional Mark Ones on time or send out imperfect ones without the z flag?

Making Perfect Machines with a Nylon + Kevlar Soft Jaw

That’s when we had an idea. Let’s print a soft jaw in kevlar (r) and have a few outside layers of nylon to guard against scratching. The kevlar (r) ensured it would be strong enough even if someone over-tightened the vise.

The MarkForged crew exported the Solid Edge model as an STL and imported it into our Eiger software. The software automatically added the reinforcing kevlar (r). It estimated a 17 hour print time. We stopped testing on one of the printers, cleaned, glued and leveled the bed. Someone hit “print” and everyone spent the night nervously watching the build.

The print was successful. We measured and tested the first tooling ever printed on a production MarkForged Mark One. The soft jaw fit in the vise perfectly.

The First Production Tooling Printed on a Mark One

Frankly, our machinist was skeptical at first. There was some grumbling and something about Kevlar (r) “feels too light to be strong.” Once he clamped down on the part in the vise, he could tell it had no give. We were able to easily carve our all 25 z flag pockets quickly.

Now the machinist is a convert. And our first Mark Ones went out with perfect pockets and no scratches.